The invention relates to a method for suppressing sporadic, short-time interferences in the processing of signals and data by means of electronic time-dependent computing, selecting, and combining circuits or of program-controlled circuits. With the use of microprocessors or microcomputers, the data are redundantly processed in two circuit systems, which are independent of each other, and in which the data are cyclically exchanged for the detection of errors and interferences. That is, the data are alternatively transferred from one system to the other and compared for agreement. Circuit configurations for implementing the method can be provided for controlling a slip-controlled brake system for automotive vehicles.
Such methods and circuit configurations are known. According to DE-OS (German Printed Patent Application) No. 32 34 637 inductive transducers are arranged at the vehicle wheels or at the axles for the control of a brake slip control system. The inductive transducers emit signals whose frequency and frequency changes represent the wheel rotational behavior. The signals are redundantly processed by means of two electronic circuit systems such as microcomputers, which are independent of each other. As long as there is no interference identical braking pressure control signals will be available at the outputs of the two systems. By way of output amplifiers or valve drivers, respectively, electronically operable multi-directional valves are connected to the output of one of the two systems. The multi-directional valves are inserted into the hydraulic lines between the master cylinder of the brake system and the wheel brakes and allow the braking pressure variation to be influenced for the purpose of slip control.
The two circuit systems of this known arrangement comprise comparators by means of which internal signals (i.e., signals generated within the system itself) are compared and checked for agreement with the signals of the second circuit system. The signals are exchanged between the circuit systems. If one of the two comparators notes a difference between the internal signal and the transferred signal of the other system, this will imply the disconnection of brake slip control even if this interference is but a one-time, short, and unimportant interference. Thus, in some cases, the reaction of monitoring and disconnection devices is overly sensitive.
It is thus an object of this invention to increase the error tolerance or interference tolerance in redundantly operated systems of the aforementioned type in a simple manner so as to ensure that the system automatically differentiates between sporadic, short-time, and harmless interferences and respectively real errors or interference of such a nature that might produce false results in the data processing.